1. Field of the Invention
This invention relates to an optical sensor for detecting light and generating a detection signal.
2. Description of the Prior Art
An optical sensor having a lens for receiving light and a photodetector for generating a light intensity signal in response to the received light is known. U.S. Pat. No. 5,432,599 discloses a temperature control system having a light intensity detection device for providing temperature compensation in accordance with the variation in angle of incident sunlight. U.S. Pat. No. 5,022,725 discloses an optical sensor including a light detector, a converging lens located between the light detector and a light source, the light rays from which are detected by the light detector, and a light shielding unit provided on a part of the converging lens. U.S. Pat. No. 4,933,550 discloses a photodetector system for producing electrical signals responsive to the orientation of a light source, such as the sun, with respect thereto utilizes a diffuser to eliminate position-dependent sensitivities of the photocathod. Moreover, U.S. Pat. No. 5,693,934 discloses a luminance detecting circuit in which plural photoinduced currents are amplified and combined onto a common current conductor, wherein the current amplifiers are turned on or off by control signals and therefore the luminance detecting circuit amplifies the current of the required photo detecting element only.
The aim of the present invention is to provide a superior optical sensor.
According to the present invention there is provided a first optical sensor including: an optical detecting unit including a plurality of photodetectors for receiving light and generating detection signals; a light amount controlling unit arranged above the optical detecting unit for controlling amounts of the light to the photodetectors in accordance with an incident angle of the light; and an weighting portion for respectively weighting sensitivities of the photodetectors and outputting an weighted detection signal from the detection signals, wherein a characteristic of the weighted detection signal varies in accordance with the incident angle, in order to obtain a desired directivity regarding incident angle (elevation angle).
In this first optical sensor, the weighting portion may include a signal processing circuit for controlling gains of the detection signals in order to obtain a desired directivity regarding incident angle (elevation angle).
In this first optical sensor, opaque films may be provided on the optical detection unit for controlling amounts of the light to respective photodetectors by controlling ratios between existence and inexistence of the opaque films per a unit area above respective photodetectors.
In this first optical sensor, a translucent film for controlling the light transmittance by controlling thicknesses of the portions of the translucent film above respective photodetectors may be provided.
In this first optical sensor, the light amount controlling unit may include a meniscus lens.
In this first optical sensor, the photodetectors may have different output characteristics respectively in response to the same amount of the light.
In this first optical sensor, the photodetectors are arranged coaxially as a second optical sensor.
In the second optical sensor, an outputting circuit for outputting one of the detection signals from one of the photodetectors arranged near the center of the photodetectors as a first sunlight amount detection signal indicative of a first amount of the light having a first directivity may be further provided, wherein the weighting portion includes a signal processing circuit for controlling gains of the detection signals and outputting a second sunlight amount signal indicative of a second amount of the light having a second directivity.
In the second optical sensor, one of the photodetectors arranged near the center of the photodetectors may be apart from the other photodetectors by a predetermined interval and the weighting portion includes a signal processing circuit arranged between one of the photodetectors and the other photodetectors.
In the second optical sensor, the light amount controlling unit controls the amounts of the light to the photodetectors such that the detection signals from the other photodetectors show a first set of magnitudes when the incident angle is substantially zero and show a second set of magnitudes when the incident angle is apart from zero which are respectively lower than the first sets of magnitudes.
In the second optical sensor, the light amount controlling unit has a shade for shading a portion of the light to the other photodetectors when the incident angle is substantially zero.
In the first optical sensor, the detection signals of a plurality of the photodetectors are summed to generate a first function signal and are combined to provide a second function signal. The first function signal is provided to control an air conditioner of a vehicle on which the optical sensor is mounted. The second function signal is provided to control turning on and off of a head lamp unit of the vehicle.
In this case, the first function signal is obtained by using a part of a plurality of the photodetectors and the second function signal is obtained by using all of a plurality of the photodetectors. Moreover, the optical sensor may further comprise a semiconductor chip including a plurality of the photodetectors which are coaxially arranged with each other. The first function signal is obtained from first one of the photodetectors arranged at a center of the photodetectors. Second one of the photodetectors arranged at the most outer peripheral position of the photodetectors and the second function signal is obtained from all of a plurality of the photodetectors.
In the second optical sensor, the detection signals of a plurality of the photodetectors are summed to generate a first function signal and are combined to provide a second function signal, and the first function signal is provided to control an air conditioner of a vehicle mounting the optical sensor. The second function signal is provided to control turning on and off of a head lamp unit of the vehicle.
In this case, the first function signal is obtained by using a part of a plurality of the photodetectors and the second function signal is obtained by using all of a plurality of the photodetectors.
Moreover, the optical sensor further comprises a semiconductor chip including a plurality of the photodetectors. The first function signal is obtained from first one of the photodetectors arranged at a center of the photodetectors and second one of the photodetectors arranged at the most outer peripheral position of the photodetectors. The second function signal is obtained from all of a plurality of the photodetectors.
According to the present invention there is provided a third optical sensor including: an optical detecting unit including a plurality of photodetectors for receiving light and generating detection signals; a light amount controlling unit arranged above the optical sensor for controlling amounts of the light to the photodetectors in accordance with an incident angle of the light; and a signal generation circuit for generating a first function signal regarding at least an incident angle of the light from one part of a plurality of the photodetectors and generating a second function signal regarding a total amount of the light from another part of photodetectors including the one part of a plurality of the photodetectors. The detection signals of a plurality of the photodetectors are summed to generate the first function signal and are combined to provide the second function signal. The first function signal is provided to control an air conditioner of a vehicle on which the optical sensor is mounted. The second function signal is provided to control turning on and off of a head lamp unit of the vehicle. The first function signal is obtained by using a part of a plurality of the photodetectors and the second function signal is obtained by using all of a plurality of the photodetectors.
In the third optical sensor, the optical sensor further includes a semiconductor chip including a plurality of the photodetectors which are coaxially arranged with each other. The first function signal is obtained from first one of the photodetectors arranged at a center of the photodetectors and a second one of the photodetectors arranged at the most outer peripheral position of the photodetectors. The second function signal is obtained from all of a plurality of the photodetectors.
In this case, the optical sensor further comprises a weighting portion for respectively weighting sensitivities of the photodetectors and outputting a weighted detection signal from the detection signals. A characteristic of the weighted detection signal varies in accordance with the incident angle. The weighting portion comprises a signal processing circuit for controlling gains of the detection signals.
According to the present invention there is provided a fourth optical sensor including: an optical detecting unit including a plurality of photodetectors for receiving light and generating detection signals; a light amount controlling unit arranged above the optical detecting unit for controlling amounts of the light to the photodetectors in accordance with an incident elevation angle of the light; a first signal generation circuit for generating and outputting a first sensor signal including data of an incident elevation angle of the light from a part of the detection signals; and a second signal generation circuit for generating and outputting a second sensor signal including data of a total amount of the light from the detection signals.
In the fourth optical sensor, the photodetectors are arranged coaxially.
In the fourth optical sensor, the photodetectors includes a first pair of photodetectors as first right and left photodetectors having a semi-circle shape. A second pair of photodetectors as second right and left photodetectors having a first ring shape. A third pair of photodetectors as third right and left photodetectors having a second semi-ring shape. The first to third right photodetectors are arranged symmetrically with the first to third left photodetectors regarding a direction on a plane on which the photodetectors are arranged. The first signal generation circuit includes a first circuit for generating a right side direction sensor signal from at least one of the first to third right photodetectors and a second circuit for generating a left side direction sensor signal from at least one of the first to third left photodetectors. The second signal generation circuit generates the second sensor signal from the first to third pairs of photodetectors.
In this case, the second left and right photodetectors are physically connected.
Moreover, a weighting unit for respectively weighting the first and second sensor signals and outputting first and second weighted detection signals may be further provided. Characteristics of the first and second weighted sensor signals vary in accordance with the incident elevation angle.
Moreover, the light amount control unit includes a first opaque ring arranged just above peripheral portions of the first pair of photodetectors to prevent the light from entering the first pair of photodetectors at a right elevation angle and a second opaque ring arranged just above the third pair of photodetectors to prevent the light from entering the third pair of photodetectors at a elevation angle.